Motor vehicle control system and method for controlling a motor vehicle

ABSTRACT

A motor vehicle control system has at least two separate control units, which are interconnected via a bus system, each control unit controlling respective individual vehicle components. The control system effectively uses the memory location and computing time resources that exist within a combination of control units, thus assuring processing of the routines that can take place in real time. Use of the existing resources is assured without additional hardware expenditure.

CROSS REFERENCE TO RELATED APPLICATIONS

Applicant claims priority under 35 U.S.C. §119 of German Application No.101 62 853.6 filed on Dec. 17, 2001. Applicant also claims priorityunder 35 U.S.C. § 365 of PCT/DE02/04579 filed on Dec. 16, 2002. Theinternational application under PCT article 21(2) was not published inEnglish.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a motor vehicle control system having at leasttwo separate control units, which are connected with one another by wayof a bus system, and a method for controlling motor vehicle componentsby means of the motor vehicle control system.

2. The Prior Art

It is generally and previously known to provide a combination of controldevices in vehicles, whereby a separate control device is provided forindividual functions (engine control, transmission control, ABS, etc.),in each instance. In this connection, the control devices are connectedby way of a bus system and can communicate with one another, exchangedata, etc. The constant expansion of functionality has the result,particularly in the case of complex control devices, such as the enginecontrol device, of rapid changes in the control device hardware, wherebythe memory space, I/O ports, and computer performance are expanded. Assoon as control devices and software are ready for series production,their capacity limits are already reached. Time-consuming andcost-intensive adaptation of the control devices to the increased demandfor memory space and computing speed, in each instance, are the result.

A method for operating a control device for a motor vehicle, in whichtwo control units are connected by way of a data bus, is previouslyknown from DE 197 50 026 A1. If it is determined, during operation ofthe control units, that one of the control devices has reached itsperformance limit, control device functions are temporarily transferredto the second control device and performed there. In this connection,the program code of the function is transmitted to this control device,or a function implemented in dual manner, that is already present on thesecond control device, is utilized. It is a disadvantage with thismethod of procedure that the entire program code has to be transmittedonce, or that the functions have to be implemented in the controldevices in dual manner. This results in additional memory requirementsand is impossible for complex functions. Furthermore, a significanteffort has to be made for temporarily transferring the functions. Thecapacity of the control device to which they are transferred must bechecked, the program structures are switched over to the control deviceto which the function is being delegated, since a new function has to belinked. This is impossible, in particular, for time-critical andsafety-relevant functions.

The use of a client/server architecture on a vehicle control devicecombination is previously known from DE 197 48 536 C2. Here, theindividual application functions are described independent of thedevices and addressed by way of a communication interface. Anycommunication between the processes therefore generates a data exchange,which must take place by way of the bus system. The individualapplication functions can therefore be implemented only once, in orderto save space, and are available to several requesters. The methodrequires an additional level (function monitor level) that functions asa central control unit as well as a central memory for the individualsystems (clients/servers). It is a problem, in this connection, that theindividual functions can be called up by several requesters at the sametime, and that the response times are lengthened due to the sequentialprocessing. Use under real-time conditions, such as for an enginecontrol device, for example, is therefore problematic.

The significant advantage of the client/server architecture lies in thecentral management of the functions, whereby these only have to beimplemented once for the applications, in each instance. The individualvehicle control devices, e.g. engine control device, transmissioncontrol device, ABS control device, have only very few functions incommon, however, so that the construction of a client/serverarchitecture for common use of the functions does not produce anydecisive advantages.

SUMMARY OF THE INVENTION

It is the task of the invention to effectively utilize the resources ofmemory space and computing time that exist within a combination ofcontrol devices of a motor vehicle and, in this connection, to assureprocessing of the routines that can take place in real time. The methodis supposed to assure utilization of the existing resources, withoutadditional hardware expenditure.

This task is accomplished, in the case of motor vehicle control systemsof the type stated, according to the invention, by means of thecharacterizing features of claims 1–8 and, in the case of methods forcontrolling a motor vehicle, of the type stated, according to theinvention, by means of the characterizing features of claims 9–16.

Usually, the processing of control functions takes place in a controldevice specifically provided for the vehicle component. Thus, forexample, the engine control algorithms such as calculation of thecharacteristic variables for injection and ignition, AGR, cooling, errormanagement, driving speed regulation, etc., are processed in the enginecontrol device, while a transmission control device is provided forcontrolling the transmission, and an ABS control device is provided forimplementing anti-lock strategies to brake the vehicle.

If the functions stored in the control device must be expanded, or ifnew functions have to be added, one rapidly reaches the limits of theindividual control devices with regard to memory space and computingcapacity, so that a new generation of control devices, having expandedmemory space and higher processing speeds, must be introduced. However,expansion of the functions does not proceed uniformly in all the controldevices, so that memory space might still be available in thetransmission control device, for example, and computing capacity is alsoavailable, while adding a new function, e.g. for direct fuel injection,to the engine control device, is not possible because its memory spaceand computing capacity are no longer sufficient. Until now, if a controldevice had reached its capacity limit with regard to memory space and/orcomputing performance, the use of a new control device took place.

It is now advantageous that according to the invention, a program thatis to be processed in a control device is divided up, whereby functionsfrom the control device that has reached its capacity limit aretransferred to a control device having available resources. In thisconnection, the program code of the function that was taken out of theprogram is transferred to the “foreign” control device. Processing ofthe transferred function also takes place on the processor of the“foreign” control device. The requirements for computing, any transfervalues, as well as the input and output variables are exchanged by wayof a bus system that connects the control devices.

It is advantageous that according to the invention, the functions thatrequire a large amount of memory space and/or computing time but forwhich no great requirements in terms of real-time capability are set arethose that are transferred out of the control devices. The overallsystem remains real-time capable, since the lengthened response timesthat result from communication by way of the bus system only affect thenon-time-critical functions that have been transferred out. By means oftransferring out non-time-critical functions, room is made for thosefunctions for which greater requirements with regard to the responsetimes are set.

The selection of the transferred functions can also be based on purelypractical considerations, in that newly added functions are transferredto a foreign control device independent of their need for memory spaceand computing time. The function to be newly implemented in thecombination of control devices is then not implemented in the controldevice that is specifically intended for the control task of the vehiclecomponent, if the latter has reached its capacity limit. This newlyadded function is transferred to a foreign control device. Thealgorithms that previously ran on the control device do not have to bechanged for this, whereby the structure that might already have beentested and proven can be maintained.

It is advantageous that according to the invention, the functions thatset low requirements with regard to the data exchange with the actualmain program are those that are transferred from a control device thatis working at its capacity limit in terms of memory space and/orcomputing time. The amount of additional data to be transmitted by wayof the bus system can therefore be kept low, and this assures a lowerload for the bus system, for one thing, and faster processing of thetransferred function, for another thing.

At present, the design of control device functions for vehicle controldevices extensively takes place using hardware-independent developmenttools such as ASCET-SD or MATLAB. In this connection, the functions aredescribed by means of block schematics, status graphs, signal links,etc. Here, the generation of the control code for a specific platformtakes place only after the hardware-independent design. The designmethod thereby makes it possible to isolate individual functions fromthe total program, in simple manner.

It is advantageous that according to the invention, if the freeresources of all of the control devices of the combination of controldevices are utilized, and if the control functions are distributed toother control devices, new control devices that have been expanded interms of computing performance and memory capacity have to be introducedonly if the resources of all the control devices that were present inthe vehicle before and were connected by way of a bus system have beenexhausted.

It is advantageous that according to the invention, functions from theengine control device, in particular, are transferred to a differentcontrol device, for example the transmission control device of thevehicle. The expansion of the engine control device that becomesnecessary due to new algorithms that have been introduced into thecontrol device, for example for direct fuel injection, or due toexpansion of existing algorithms, is postponed by means of transfer ofnon-time-critical functions, such as driving speed regulation and/or airconditioning system control and/or engine cooling/fan control and/oranti-theft lock, until all the control devices arranged in thecombination of control devices of the vehicle have been utilized totheir full capacity in terms of computing time and memory space.

The motor vehicle control system according to the invention offers thepossibility of transferring a large number of functions from one controldevice to one or more other, different control devices. In thisconnection, distributing the functions is possible without any change inthe existing control devices and their connections with one another. Thepossibility therefore exists of fitting expanded and/or additionalalgorithms into an existing control device structure. New algorithms cantherefore not only be introduced in connection with a new design, butalso retrofitted into existing structures, as long as resources withregard to memory space and computing performance are still available inone of the control devices that is part of the combination of controldevices.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, am exemplary embodiment of the invention will bedescribed using a drawing.

The sole drawing shows an exemplary embodiment of the motor vehiclecontrol system according to the invention.

Referring to the drawing, a control device Si that serves to control anengine 1, a control device S2 that controls a transmission that belongsto the engine, and a control device Sx, which controls the brakepressure of the vehicle brakes, for example (ABS control device) areshown as examples. The control devices Sl–Sx are connected with oneanother by way of a bus system 5 of the vehicle, e.g. a CAN bus. SensorsSM and actors AM are arranged on the engine 1, the measurement andcontrol signals SMl–SMx and AMl–AMx of which are applied to the controldevice S1, i.e. are controlled by the latter. Sensors SG and actors AGare arranged on the transmission 2, the measurement and control signalsSG1–SGx and AGl–AGx of which are applied to the control device S2, i.e.are controlled by the latter. Sensors SD and actors AD are arranged onthe brake pressure control 4, the measurement or control signals SMl–SMxand ANl–AMx of which are applied to the control device Sx, i.e. arecontrolled by the latter. Furthermore, the signals DZl–DZ4 of the wheelrotation speed sensors 3 are applied to the control device.

Programs for controlling a vehicle component are stored in the controldevices S1–Sx, in each instance.

A program HPM for engine control is stored in the control device S1. Theprogram consists of the functions FM1–FMx, which determine parametersand/or process measurement values of the sensors SM and/or determinecontrol variables for the actors AM. The program HPM for controlling theengine runs on the processor of the control device 1. As alreadydescribed, greater demands on the control device S1 with regard tomemory space and computing capacity can come about as the result ofnecessary expansion of the functions FM1-FMx, or as the result of newlyadded functions. If the device has reached its capacity limit, it wouldhave to be replaced with a new control device provided with expandedmemory space and a greater computing capacity. However, additionalcontrol devices S2–Sx are present in the vehicle. A program HPG, whichconsists of functions FG1–FGx for controlling the transmission is storedin the control device S2. The program HPG is carried out on theprocessor of the control device 2. Another program HPB having functionsfor controlling the brake pressure FB1–FBx is stored in the controldevice Sx, whereby it is carried out on the processor of this controldevice Sx.

If an increased demand for computing and/or memory capacity in thecontrol device S1 is required, memory space and computing capacity canbe made available in the control device 1 by means of transferring outindividual functions, such as the function FM4, in this example, to adifferent control device, namely S2 here.

The function FM4, which contains the driving speed regulation, forexample, is then stored on the control device S2 for controlling thetransmission, and runs on the processor of this control device S2. Thenecessary parameters are made available by the control device S1, by wayof the bus system 5. The parameters calculated by the function FM4, forexample an injection amount necessary in order to implement the desiredspeed of the vehicle, can be called up by the control device S1 by wayof the bus system 5. The parameters calculated in the control device S2in this manner are processed further in the control device S1, i.e. theycan form the setting variables for the actors AM for controlling theengine. The function FM4 is linked with the program for controlling thetransmission, HPG, but runs extensively isolated from the latter interms of data exchange.

As shown with the example of the function FM4, other functions ofcontrolling the engine can also be transferred to the control device S2for controlling the transmission. It is also possible to transfer thefunctions to other control devices, for example the control device Sxthat is shown. Another possibility is to divide several functions of theengine control device FM1–FMx, which are to be transferred out, amongdifferent control devices, so that parts of the engine control arestored and carried out in the transmission control device SG and otherparts in the control device Sx.

In one embodiment, the functions that have been transferred out of thecontrol device Si have a lower number of input and/or output variablesthan the functions that are stored in the control device and are carriedout within the program that runs on this control device Si. In addition,the function or functions that have been transferred out of the controldevice Si and run on the other control device S2 or the other controldevices S2–Sx may have a lower number of input and/or output variablesthan the functions that are stored in the control device 51 and may becarried out within the program that runs on this control device S1.

REFERENCE SYMBOL LIST

-   1 engine-   2 transmission-   3 wheel rotation speed sensor-   4 brake pressure control-   5 bus system-   S1 control device for controlling the engine-   S2 control device for controlling the transmission-   Sx control device for controlling the brake pressure-   HPM program for controlling the engine-   HPG program for controlling the transmission-   HPB program for controlling the brake pressure-   FM1–FMx functions for controlling the engine-   FG1–FGx functions for controlling the transmission-   FB1–FBx functions for controlling the brake pressure-   SM1–SMx signals of the sensors for controlling the engine-   SG1–SGx signals of the sensors for controlling the transmission-   DZ1–DZ4 signals of the wheel rotation speed sensors-   SD1–SDx signals of the pressure control-   AD1–ADx signals for controlling the actors for brake pressure    control-   AG1–AGx signals for controlling the actors for engine control-   AM1–AMx signals for controlling the actors for transmission control-   SM sensors for controlling the engine-   AM actors for controlling the engine-   SG sensors for controlling the transmission-   AG actors for controlling the transmission

1. A motor vehicle control system comprising at least first and secondseparate control devices interconnected via a bus system, each controldevice controlling an associated individual vehicle component, whereinsaid first control device has a first processor and at least one firstcontrol device program stored in said first control device having atleast one function specified in a program code carried out by said firstprocessor that is transferred from said first control device to saidsecond control device and is linked with a program sequence of a secondcontrol device program running on the second control device andprocessed on a second processor of the second control device, said atleast one function having input and output variables transmittablebetween the second control device and the first control device via thebus system; wherein several functions of the first control deviceprogram that is stored on the first control device and runs on saidfirst control device are transferred from said first control device to arespective one of a plurality of transferee control devices, eachfunction transferred from said first control device having a respectiveprogram code stored in a respective one of the plurality of transfereecontrol devices, each function of the respective transferee controldevice being linked with a respective control device program that runson the transferee control device, whereby the functions transferred fromsaid first control device are thereby distributed over the transfereecontrol devices with regard to memory storage in memory andimplementation; and wherein the functions transferred out of the firstcontrol device are new functions that have been added to existingfunctions previously stored in the first control device in the course ofthe development of the first control device and have been isolated fromsaid existing functions.
 2. The motor vehicle control system accordingto claim 1, wherein the functions that have been transferred out of thefirst control device have longer response times than the functions thatare stored in the first control device and are carried out within thefirst control device program that runs on the first control device. 3.The motor vehicle control system according to claim 1, wherein thefunctions that have been transferred out of the first control devicehave a lower number of input or output variables than the functions thatare stored in the first control device and are carried out within thefirst control device program that runs on the first control device. 4.The motor vehicle control system according to claim 1, wherein thefunctions that have been transferred out of the first control devicehave a greater need for memory space than the functions that are storedin the first control device and are carried out within the first controldevice program that runs on the first control device.
 5. The motorvehicle control system according to claim 1, wherein the first controldevice from which the program code of at least one function that hasbeen transferred out of the first control device program that runs onthe first control device controls the vehicle engine.
 6. The motorvehicle control system according to claim 5, wherein the functions thathave been transferred out of the first control device program that runson the first control device regulate speed or cool the engine or controlthe fan or implement an anti-theft lock or operate a pre-glow functionfor glow pins or regulate exhaust gas recycling or recognize a driver'swishes by way of the gas pedal or implement error management.
 7. Themotor vehicle control system according to claim 1, wherein the secondcontrol device to which the program code of said at least one functiontransferred out of the first control device program that runs on thefirst control device has been transferred controls the transmission. 8.A method for controlling a motor vehicle having a control systemcomprising at least first and second control devices interconnected viaa bus system, each control device controlling an associated individualvehicle component, wherein the control devices have independent programscomprising a plurality of functions running in the control devices, saidmethod comprising the steps of: (a) transferring from the first controldevice to the second control device via the bus system at least onefirst control device program having at least one function forcontrolling a vehicle component associated with the first control devicestored in the first control device, the at least one function havinginput and output variables transmitted between the first control deviceand the second control device via the bus system; (b) linking the atleast one function of the at least one first control device program to asecond control device program running in the second control device; andc) carrying out the at least one function via the second control deviceprogram; wherein several functions of the first control device programthat is stored on the first control device and runs on the first controldevice are transferred from the first control device to a respective oneof a plurality of transferee control devices, each function transferredfrom the first control device having a respective program code stored ina respective one of the plurality of transferee control devices, eachfunction being carried out within a respective control device programthat runs on the respective transferee control device, and the functionstransferred from the first control device to the respective transfereecontrol devices make output variables available for the first controldevice program that is running on the first control device via the bussystem; and wherein the functions transferred out of the first controldevice are new functions that have been added to existing functionspreviously stored in the first control device in the course of thedevelopment of the first control device and have been isolated from saidexisting functions.
 9. The method for controlling a motor vehicleaccording to claim 8, wherein each function that has been transferredfrom the first control device and run on the respective transfereecontrol device has a longer response time than the functions that arestored in the first control device and are carried out within the firstcontrol device program that runs on the first control device.
 10. Themethod for controlling a motor vehicle according to claim 8, whereineach function that has been been transferred from the first controldevice and run on the respective transferee control device has a lowernumber of input or output variables than the functions that are storedin the first control device and are carried out within the first controldevice program that runs on the first control device.
 11. The method forcontrolling a motor vehicle according to claim 8, wherein each functionthat has been been transferred from the first control device and run onthe respective transferee control device require more memory space thanthe functions that are stored in the first control device and arecarried out within the first control device program that runs on thefirst control device.
 12. The method for controlling a motor vehicleaccording to claim 8, wherein the program code of at least one functionis transferred out of the first control device program that serves tocontrol an engine, and the first control device program runs on thefirst control device that controls the engine.
 13. The method forcontrolling a motor vehicle according to claim 12, wherein at least onefunction runs on at least one of the transferee control devices the atleast one function having been transferred from the first control deviceprogram that runs on the first control device and serving to regulatespeed or control the air conditioning system or cool the engine orcontrol the fan or implement an anti-theft lock or operate a pre-glowfunction for glow pins or recognize a driver's wishes by way of the gaspedal or regulate exhaust gas recycling or implement error management.14. The method for controlling a motor vehicle according to claim 8,wherein one of the transferee control devices running at least onefunction transferred from the first control device program that runs onthe first control device controls the transmission.